WASHINGTON  Americans continued in March to increase credit card debt at a double-digit rate, a sign that consumers may be looking to plastic to get them through lean times.

According to the Federal Reserve, consumer debt  a broad class of borrowing that includes just about everything except mortgages  grew in March at an annualized rate of 4.7 percent.

The figure is less than half the growth rate of February and below what most economists were expecting. But the monthly growth in consumer debt is notable because credit cards accounted for all of it. Credit card debt grew at an annualized rate of 11.7 percent in March, the third consecutive month of double-digit growth.

Fed data don't tell whether the March growth in credit card debt is related more to a new spending spree or a slowdown in the paying off of old credit card debt.

As a result, economists say it's a matter of conjecture whether consumers were scrambling to keep up as the economy sinks or whether they were simply accommodating big expenses, such as heating bills, by paying a little less on their credit cards.

Steven Wood, economist at FinancialOxygen, says the increased credit card debt is a sign that a slowing economy is placing stress on households as unemployment rises and income growth slows.

Meanwhile, non-credit card consumer debt  for such things as automobiles, home improvements and schooling  declined in March at an annualized rate of 0.6 percent, the Fed says. Overall, the $6.1 billion increase in consumer debt during March is the smallest registered by the Fed since October 1999.

Lynn Reaser, chief economist for Bank of America Asset Management, says the decline in non-credit-card debt is largely a reflection of earlier reports of a downturn during March in retail sales, including auto sales.

The March figure was probably moderated further, she says, by consumers rolling miscellaneous debts into a refinanced home mortgage and from taxpayers using income tax refunds to pay off loans.